A semiconductor light emitting device such as a light emitting diode (LED) is a device including a material that emits light through the application of electrical energy thereto, in which energy generated by electron hole recombination at semiconductor junctions is converted into light to be emitted therefrom. LEDs are commonly employed as light sources in general illumination devices, display devices, and the like, and the development of LEDs has accelerated.
Recently, the development and employment of gallium nitride-based LEDs has increased, and mobile device keypads, vehicle turn signal lamps, camera flashes, and the like, using such a gallium nitride-based LED, have been commercialized, and in line with this, the development of general illumination devices using LEDs has accelerated.
Like the products to which they are applied, such as a backlight unit of a large TV, a vehicle headlamp, a general illumination device, and the like, products in which LEDs are utilized are gradually moving toward large-sized products having high outputs and high efficiency, and thus, the characteristics of LEDs used in such products are required to satisfy the high level characteristics required of the LEDs.